#include <bits/stdc++.h>
using namespace std;
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using namespace atcoder;
#endif
using ll = long long;
using ld = long double;
#define all(s) (s).begin(),(s).end()
#define vcin(n) for(ll i=0;i<ll(n.size());i++) cin>>n[i]
#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
#define rep(i, n) rep2(i, 0, n)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define drep(i, n) drep2(i, n, 0)
#define rever(vec) reverse(vec.begin(), vec.end())
#define sor(vec) sort(vec.begin(), vec.end())
#define fi first
#define se second
#define P pair<ll,ll>
const ll mod = 998244353;
//const ll mod = 1000000007;
const ll inf = 2000000000000000000ll;
static const long double pi = 3.141592653589793;
void YesNo(bool a){if(a){cout<<"Yes"<<endl;}else{cout<<"No"<<endl;}}
void YESNO(bool a){if(a){cout<<"YES"<<endl;}else{cout<<"NO"<<endl;}}
template<class T,class U> void chmax(T& t,const U& u){if(t<u) t=u;}
template<class T,class U> void chmin(T& t,const U& u){if(t>u) t=u;}
ll modPow(ll a, ll n, ll mod) { ll ret = 1; ll p = a % mod; while (n) { if (n & 1) ret = ret * p % mod; p = p * p % mod; n >>= 1; } return ret; }

int main() {
  /* mod は 1e9+7 */
  ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
  cout<< fixed << setprecision(10);
  ll n;
  cin>>n;
  string s;
  cin>>s;
  ll a=0,b=0,c=0;
  vector<ll> A,B,C;
  for(int i=0;i<n;i++){
    if(s[i]=='A'){
      a++;
      A.push_back(i);
    }
    if(s[i]=='B'){
      b++;
      B.push_back(i);
    }
    if(s[i]=='C'){
      c++;
      C.push_back(i);
    }
  }
  if(a*b*c==0){
    cout<<1<<endl;
    return 0;
  }
  std::random_device seed;
  std::default_random_engine engine(seed());
  std::uniform_int_distribution<long long> x(0,int(A.size())-1),y(0,int(B.size())-1),z(0,int(C.size())-1);
  bool can=false;
  for(int i=0;i<100;i++){
    ll p=x(engine),q=y(engine),r=z(engine);
    if((A[p]<B[q]&&B[q]<C[r])||(B[q]<C[r]&&C[r]<A[p])||(C[r]<A[p]&&A[p]<B[q])){
      can=true;
      break;
    }
  }
  if(!can){
    cout<<1<<endl;
  }
  else{
    ll ans=1;
    for(int i=1;i<=n;i++){
      ans*=i;
      ans%=mod;
    }
    for(int i=1;i<=a;i++){
      ans*=modPow(i,mod-2,mod);
      ans%=mod;
    }
    for(int i=1;i<=b;i++){
      ans*=modPow(i,mod-2,mod);
      ans%=mod;
    }
    for(int i=1;i<=c;i++){
      ans*=modPow(i,mod-2,mod);
      ans%=mod;
    }
    ans-=n;
    ans+=mod;
    ans%=mod;
    cout<<ans<<endl;
  }
}